Sensors are known devices for converting information, in the form of a physical quantity (of variable input) into a physical quantity (of variable output) of identical or different type, measurable in accordance with a defined law. These types of sensors generally include a sensor, i.e. a primary element of a measurement chain, configured to convert the variable input into a measurable signal, and a conditioning circuit, which receives the measurable signal as input and provides it as output transformed in accordance with a defined law, to make it available to the user.
Electrical systems are known to use current sensors and voltage sensors for various purposes, for example for energy measurements, for protection, for fault localization, etc.
U.S. Pat. No. 6,670,799 discloses a method and/or apparatus for measuring current in a high voltage current carrier and suggests a solution for the phase compensation of a Rogowski coil-based current transducer relied on the use of a proper passive circuit.
U.S. Pat. No. 5,473,244 discloses a different apparatus for measuring voltages and currents using non-contacting sensors.
WO99/54740 discloses a current measuring device comprising a Rogowski coil.
In particular, known voltage sensors consist of transformers or capacitive or resistive dividers, their purpose being generally to reduce the primary voltage to values compatible with the particular use for which they are intended. Known current sensors consist of current transformers or Hall effect sensors or anti-inductive shunts, their function being to reduce the primary current to values compatible with the particular use for which they are intended.
A basic requirement for a current or voltage sensor for the aforesaid uses is adequate precision, which is currently achievable only at the expense of sensor weight, overall size, cost, limitations on its field of application, and generally a series of limitations on its characteristics and/or performance, and the consequent need for the producer to compromise.
In particular, with regard to precision, a sensor must be able to provide as output an electrical quantity representative of the input quantity with phase and ratio errors contained within narrow predetermined limits.